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#26 bobhen

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Posted 08 June 2019 - 09:54 AM

I’ll relate my experience.

 

I live in an extremely light polluted location outside Philadelphia, PA.

 

I have a NV Devices Micro with a green tube. I’ve been doing NV astronomy for 3 years. In that time I have not used a conventional eyepiece for deep sky viewing.

 

With NV you will experience the sky in a new way. The only comparison is observing under a really black sky and even then you don’t get the amplification with conventional glass like you do with NV.

 

Pick the best tube you can afford, green or white. The green will not bother you.

 

Just about any scope will work but you will probably want at least 3.

 

A scope for wide fields, like a 4” F5 refractor (can be an cheap achromat) or 6” F4 or F3 Newtonian. I use a 4” F5 achromat reduced to F3.5.

 

A scope that gets you some image scale for small targets like globular clusters, like a 10 to 12” f 5 Newtonian or an 8 to 11-inch SCT (which can be reduced to F5, 6, or 7) I use a Mewlon 210 reduced to F8.

 

A camera lens or repurposed 50mm guide scope for extreme wide fields. These can be handheld for sweeping and quick looks. I use a 50mm repurposed guide scope.

 

Some images below...

 

The optical train I use. The 4” f5 refractor, GSO focuser, 2” Astro-Physics diagonal, .7 reducer, 2” to 1.25” diagonal adaptor then the Micro. The Micro has a C-mount to 1.25-inch adaptor that replaces the lens that the Micro comes with. On the end of the adaptor is a 1.25” filter. For non-nebula objects I use a 685 Pass filter. For nebula objects I use a .6 nm Ha CCD filter.

 

My 50 mm repurposed guide scope.

 

The Micro in the diagonal of my 4" F5 achromat.

 

HERE is a website with lots of info to get started

 

If you go the NV astronomy route, you will not regret it.

 

Hope this helps.

 

Bob

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Edited by bobhen, 08 June 2019 - 10:43 AM.

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#27 Joko

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Posted 08 June 2019 - 10:42 AM

 For non-nebula objects I use a 285 Pass filter.

Hello bobhen, you probably mean 685 Pass filter instead of 285. smile.gif



#28 bobhen

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Posted 08 June 2019 - 10:44 AM

Hello bobhen, you probably mean 685 Pass filter instead of 285. smile.gif

Sorry typo - fixed.

 

bob



#29 bdg

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Posted 08 June 2019 - 06:10 PM

Which vendor sells Mod3 manual gain device with tested spec sheet.



#30 Eddgie

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Posted 08 June 2019 - 06:26 PM

The Mod 3 is not a factory made complete device.   It is a body that the dealer buys from AB Night Vision.  The dealer installs a tube into the body and adds the eyepiece (which is the same eyepiece as is used on the PVS-14). 

 

Just about all modern high end civilian tubes should have a spec sheet with it. If they can't provide a spec sheet, then look elsewhere.  When you pay what amounts to about $3700 for just an image intensifier tube (the Mod 3 housing is only a few hundred dollars) you should expect the dealer to provide the spec sheet.

 

I like Ultimate Night Vision (ask for Richard) but TNVC is another dealer that people use, and there are many other dealers out there.  

 

Night Vision Devices used to deal primarily in ITT/Harris thin film tubes, but they have in the past told me that they can also get L3 (and now they are all the same company) and NV Devices offers a 10 year warranty on their products, and can be cost competitive with the others.  If you were looking for thin film, this might be the right dealer.

 

Old military contract tubes will not have a spec sheet.   Their performance is pretty much set by the tube type on the tube (10160 D/UV for example).

 

For high end civilian tubes though, the dealers get spec sheets.  If they don't want to give it to you, then they are trying to sell you a tube that they think you will be happy enough not to return. 


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#31 Eddgie

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Posted 08 June 2019 - 06:35 PM

And this.  When I started my NV journey, I quickly became agitated by the way a lot of dealers behaved.  Many of these dealers simply classify their tubes in a "Silver/Gold/Platinum" kind of marketing modely.  You don't really know what the difference is between them, or what the performance of the "Platinum" level tube will be, only that the dealer sells on the basis of "Good/Better/Best" and their "Best" tube could simply be a upper mid range tube, and well short of the performance of a modern high end tube.

 

Now ITT/Harris used to classify the tubes by model number, and they had a web page that provided the minimum specs for each mode, so if you bought a model "Y" tube, you could estimate the performance as being between the model "X" specs and the model "Z" specs so the model number was a pretty decent way to determine about what performance the tube would have. Here is an example:

 

https://www.harris.c...r-specsheet.pdf


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#32 Eddgie

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Posted 08 June 2019 - 06:44 PM

And this should be an eye opener for many people using filmless tubes.   As I have said in the past, just because it is a filmless tube, do not expect it to outperform the best thin film tubes.

 

Here is an example.  The F9800 M24H is the top end thin film tube.    Many people buy filmless tubes with an SN of 33 or 34 thinking that thin film tubes won't be as good, but as can be seen in this spec sheet, the  signal to noise ratio range of the F9800 M24H with 64 line pair resolution is between 34.4 and 37.5.

 

The white phosphor version of this tube is the F9400 M24H.

 

https://www.harris.c...r-specsheet.pdf

 

Sadly this is the tube I want to buy, but I can't seem to get anyone to sell one to me.   I don't know why.  Perhaps it is going mostly to LE. 


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#33 bdg

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Posted 08 June 2019 - 07:21 PM

Many thanks Eddgie. Now, coming from refractor world where heated debates regarding test reports are common occurrence, how to be sure about on the validity of  spec results provided by the vendor. Does the spec sheet comes directly from the factory tied to the individual tube being sold.


Edited by bdg, 08 June 2019 - 07:23 PM.


#34 Vondragonnoggin

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Posted 08 June 2019 - 07:48 PM

Many thanks Eddgie. Now, coming from refractor world where heated debates regarding test reports are common occurrence, how to be sure about on the validity of  spec results provided by the vendor. Does the spec sheet comes directly from the factory tied to the individual tube being sold.

Some vendors have testing equipment, some don’t. The tube manufacturer will have the best testing equipment, but how many vendors want complete sheeted tubes is not readily apparent. The best vendors will have their own testing equipment. You need a vendor that also understands what you mean by clean tubes. Clean to an astronomer is not the same as Mil-Spec clean. Mil-Spec clean will have a certain number of spots in zone 2 and 3 with a very small maximum size as acceptable for clean. You have to specify to the vendor that you want zero spots if that is the minimum you will accept. Generally a Mil-Spec clean tube will still be good for astronomy. No spots of any size in zone 1

 

They use testing machines like this to get the numbers.

 

https://www.electro-...ision-Test-Sets


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#35 bdg

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Posted 08 June 2019 - 08:47 PM

Some vendors have testing equipment, some don’t. The tube manufacturer will have the best testing equipment, but how many vendors want complete sheeted tubes is not readily apparent. The best vendors will have their own testing equipment. You need a vendor that also understands what you mean by clean tubes. Clean to an astronomer is not the same as Mil-Spec clean. Mil-Spec clean will have a certain number of spots in zone 2 and 3 with a very small maximum size as acceptable for clean. You have to specify to the vendor that you want zero spots if that is the minimum you will accept. Generally a Mil-Spec clean tube will still be good for astronomy. No spots of any size in zone 1

 

They use testing machines like this to get the numbers.

 

https://www.electro-...ision-Test-Sets

Thanks 1 Dragon. It appears to me I should do more research before committing to buy. Is there a reference specs to aim for taken from the tube specs thread.



#36 Vondragonnoggin

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Posted 08 June 2019 - 08:50 PM

Some vendors will also just list Figure Of Merit which is S/N x lp/mm. Maybe they get sent full devices they don’t actually touch or customize and that is what the vendor sends to them. Possibly only tested for a few criteria.

 

example is FOM1600 = 25 S/N, 64 lp/mm most likely. Could also mean 22.2 S/N, 72 lp/mm, but generally if gen 3 and only listing FOM, assume its 64 lp/mm

 

FOM1350 = S/N 21, 64 lp/mm

 

Some people only list Omnibus contract if it was a contract tube. Omni VII, Omni VIII, Omni VI, Omni IV, etc

 

Those listed like that will have a minimum requirement for whichever was stated acceptable for the Omnibus contract so if someone says “this one is an Omni VII tube” you can look up specs for the minimum acceptable for type of tube and contract. Usually will have an NSN string that is readable for example:

 

NSN: 5855-01-504-4589 (MX-10130D) NSN: 5855-01-504-4590 (MX-11769)

 

The NSN for the MX-10130D is approx Omni IV/V S/N 21, PCR 1800, halo 1.25, 64 lp/mm are minimums

 

Tubes can also have contract ID and cage numbers. If they have all three legible, it’s easier to identify.



#37 Vondragonnoggin

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Posted 08 June 2019 - 09:01 PM

Thanks 1 Dragon. It appears to me I should do more research before committing to buy. Is there a reference specs to aim for taken from the tube specs thread.

If you contact the vendors Eddgie referenced and tell them you want a good astronomy tube that is a clean-clean tube, not Mil-Spec clean, and highest PCR, S/N, lp/mm and lowest EBI and halo you should be fine. Take an average from the tube specs thread for L3 tube in filmless white phosphor and just see what they can come up with or how much wait time is acceptable to you for the tube you will be happy with.

 

You have to decide if you are a really discerning optics critic or not to gauge what will be acceptable.

 

Some of the stated minimum acceptable by members here would have left me waiting for years to get into this though.

 

I started with Omni IV tubes and I was ecstatic on the results - that can be verified by my posts back then. In no way was I turned off on Night Vision astronomy by a less than perfect tube

 

There is also the matter of EBI numbers increasing in hot weather but no one complains about summer Milky Way or summer nebulae views. Also the matter of real S/N coming through in narrowband Ha - if you have a spanking tube that’s S/N of 37 but use a 12nm Ha filter the actual Ha S/N coming through won’t appear any better than a 28 S/N tube using a 7nm Ha filter. The narrower notches provide higher S/N on Hydrogen Alpha at the expense of scintillation. Some will take the hit on less signal coming through in order to also get less scintillation or have more stars come though that a very narrow notch might block.

 

There is nuance to performance.



#38 Vondragonnoggin

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Posted 08 June 2019 - 09:24 PM

bdg- it’s very much like the refractor forum when it comes to tubes. The guy with the Astrozap refractor is still seeing a lot of goodies while the Takahashi guy will pay for the diminishing returns to get the best. 

 

There is is nothing I can think of offhand that I couldn’t see with a FOM1350 tube that I saw with a FOM2000 tube (72 lp/mm)

 

It was a noticeable increase in performance by clarity and less scintillation though. I was able to see better with the higher spec tube by way of less noise and scintillation and threshold objects raising higher over the noise floor of background noise. I generally narrowed the Ha notch and just put up with more scintillation with the older tubes. Some would not find it acceptable I’m sure. The difference to me was seeing it at all with NV vs not ever getting a chance to see it from my heavy lp location and small scopes I use with regular eyepieces. 

 

So go for the best best you can get for what you are willing to spend, but if you are looking at a wait time of a year or even 6 months, maybe get a Mod 3 housing and find a used tube to get started with and be on a wait list for a best tube. Or an NVD Micro and upgrade the tube later. I have upgraded tubes in several devices and really glad I didn’t wait. Enjoyed the views the entire time.

 

pvs-7’s give some great views and have specs no where near what current mod 3 supertubes are getting. Really fun to have an NV binoviewer.

 

Also - while it would be entirely impractical for military use, I still think a cold finger developed for astronomy applications to bring EBI to lowest even in summer heat months would be cool. I’m sure it’s never even done because of the small number of astronomy application users, but if you could bring the tube to temps you get in cold winter viewing, the clarity would be substantially better.

 

Im finally getting a clear night for a few hours at least and really want to use my NV eyepieces but - Jupiter, opposition. It’s going to be regular eyepieces, mak, and binoviewer.  cool.gif


Edited by Vondragonnoggin, 08 June 2019 - 09:31 PM.

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#39 11769

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Posted 08 June 2019 - 09:50 PM

As far as specifications go I have a slightly different recommendation.  I agree low EBI (<1) is an absolute must have.  Since 64 lp/mm is a given, my next priority is a Photocathode Response (PR) of >2200.  SN is used by vendors to price their devices and is always listed in linear units.  When converted to dB there really isn't a very big difference when going from SN 25 to SN 30 (in dB it is 28 going to 29.6).  A device with a SN rating of 25 is priced quite a bit lower than the 30 but with good PR and EBI numbers can be a terrific performer.

Comparing tube SNR after converting to dB is the way to do it. There very much is an asymptotic effect to increasing tube SNR and looking at it in terms of dB tells the full story. I think your ranking of tube performance is spot on. I come from an RF world and thinking about image tubes from the standpoint of an RF amplifier that's positioned first in a system is very helpful., 

 

I'm glad everyone is worried about EBI and how it can increase on a summer night. Without checking my notes, I seem to recall that EBI doubles for every 4C increase in temp. Even my highish EBI tubes work wonderfully in winter. I like the idea mentioned of making a cold finger for an image tube. Probably fairly doable and the temperature drop does not need to be considerable. There's a long history of cooling PMTs to reduce dark current. Same exact phenomenon with the same cure. 



#40 bdg

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Posted 09 June 2019 - 01:55 AM

Some vendors will also just list Figure Of Merit which is S/N x lp/mm. Maybe they get sent full devices they don’t actually touch or customize and that is what the vendor sends to them. Possibly only tested for a few criteria.

 

example is FOM1600 = 25 S/N, 64 lp/mm most likely. Could also mean 22.2 S/N, 72 lp/mm, but generally if gen 3 and only listing FOM, assume its 64 lp/mm

 

FOM1350 = S/N 21, 64 lp/mm

 

Some people only list Omnibus contract if it was a contract tube. Omni VII, Omni VIII, Omni VI, Omni IV, etc

 

Those listed like that will have a minimum requirement for whichever was stated acceptable for the Omnibus contract so if someone says “this one is an Omni VII tube” you can look up specs for the minimum acceptable for type of tube and contract. Usually will have an NSN string that is readable for example:

 

NSN: 5855-01-504-4589 (MX-10130D) NSN: 5855-01-504-4590 (MX-11769)

 

The NSN for the MX-10130D is approx Omni IV/V S/N 21, PCR 1800, halo 1.25, 64 lp/mm are minimums

 

Tubes can also have contract ID and cage numbers. If they have all three legible, it’s easier to identify.

So these tubes are primarily made for the govt and surplus/rejects end up for civilian market. It’s impressive you, Eddgie, Peter and others have toiled to bring NV somewhat mainstream for astronomy, I feel this is a revolutionary technology that would change amateur astronomy but still sifting through shenanigans is not optional for newbie’s before splurging $5k. 


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#41 Eddgie

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Posted 09 June 2019 - 11:57 AM

EBI Is indeed a critical value, and all other things being more or less the same (a hundred or two hundred PCR, 2 or 3 SN, mid 60,000 gain) then a big difference in EBI would should be the decision maker.

The thing though is that most tubes I am seeing people buying are simply good all around tubes with no major weakness and no major strength, and any such tube will provide super fun viewing.   

 

I would not get hung up in small difference in performance characteristics.

 

There is one exception though, and that is if the observer does much of their viewing in really hot conditions.  I am such an observer.  I live in Austin Tx, and on a hot summer night, my temps often don't fall below 90F until after I my sessions are done.  Since my own great joy is the summer Milky Way, EBI was a huge factor in my own decision.   My tubes have EBI values of .1 and .2.  Now in every other way, these are non-remarkable tubes with (by astronomy standards).  Photocatode is in the range of 2200, SN is in the 32 range, and gain in in the 64K range.   In other words, in all other ways, these tubes are pretty average higher end L3 filmless tubes. 

 

And that shows when Peter and I have done sessions together.  Peter's tube has a higher SN, but more importantly I think, his tube has a gain of close to 70,000. When we have observed under cooler conditions (40s to 50s) his tubes have produced better views than mine.  I think his EBI is in the .7-1 range, so not super good, but not at all bad.   When it is cooler though, even a slight drop in EBI, combined with the very high gain (nothing to do with SN really) make for better views of galaxies.

 

A lot of people dismiss gain in favor of SN, and I think that is a mistake. The only time the noise is a big factor is when you are running heavy filters, and when you are running heavy filters, in my own opinion, gain and EBI are perhaps going to be more important than a super high SN.

 

My advice for most people is that any higher end tube with reasonably good specs will provide for a wonderful viewing experience.

 

I would look for SN of 30 or higher (and to me, SN is not really the most important spec) gain of 65,000 or higher, and EBI of .6 or lower. I would trade some SN for some EBI, and I would trade some SN for gain.    Gain is what makes the signal stronger, and the stronger a signal is for a given amount of noise, the less the noise will interfere with it.   EBI is what set the threshold, but if the gain is too low, the threshold is higher.   A high gain means that a weak signal can stay above the EBI level.

 

Noise is to me maybe the least important attribute.  I owned a PVS-7 with a gain of 32, but the EBI was 1.99.  This tube was not effective for nebula observing, though it was fine for general observing.  I own a PVS-7 with probably 23 to 25 gain, but the EBI is probably 1.3 or 1.4, and it works for nebula mu  ch better than the tube that had SN of 32. I learned my lesson.  SN by itself  should not be the decision making factor.

 

So, EBI is important, but as long as the EBI is reasonable (ideally less than 1, but .6 or better would be even more desirable) and SN is decent (30 or above) and the gain is high (65000 or above) the tube will be enjoyable to use on all targets.  

 

If most observing is done in colder temps, that takes the pressure off of EBI, but low EBI does set the threshold (all other things being equal) and a really low EBI is very important for threshold type work(dim nebula or dim galaxies) in hot conditions.  Seeing a galaxy with a lot of scintillation in the view is in my own opinion better than not seeing the galaxy in a washed out view with less scintillation.  SN over 30 will generally give excellent views even with heavy filters if the EBI is low and gain are still reasonably high. Don't sacrifice EBI and gain for a super high SN.  In a perfect world, you would get everything, but in the real world, most people would not be able to have the patience for a true unicorn tube (High SN, High Gain, super low EBI).

 

Again, most of the people that are buying tubes are not getting super tubes, and most will say that they are very pleased.  The difference from these tubes and the six month wait tubes is not all that great, and unless the EBI is pretty low after waiting six months, having a hot photocathode and high SN is not necessarily going to get you a better view than a slightly lower SN and Photocathode, but with a decently low EBI.


Edited by Eddgie, 09 June 2019 - 12:49 PM.


#42 11769

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Posted 09 June 2019 - 01:42 PM

A lot of people dismiss gain in favor of SN, and I think that is a mistake. The only time the noise is a big factor is when you are running heavy filters, and when you are running heavy filters, in my own opinion, gain and EBI are perhaps going to be more important than a super high SN.

 

My advice for most people is that any higher end tube with reasonably good specs will provide for a wonderful viewing experience.

 

I would look for SN of 30 or higher (and to me, SN is not really the most important spec) gain of 65,000 or higher, and EBI of .6 or lower. I would trade some SN for some EBI, and I would trade some SN for gain.    Gain is what makes the signal stronger, and the stronger a signal is for a given amount of noise, the less the noise will interfere with it.   EBI is what set the threshold, but if the gain is too low, the threshold is higher.   A high gain means that a weak signal can stay above the EBI level.

 

Not quite. Any time conditions justify prioritizing EBI and gain, prioritizing EBI and PC response will give you a bigger bang for the buck. A higher PC response means that the PC produces more electrons for the same optical input signal. A stronger electron signal prior to amplification is better than amplifying more strongly a weaker signal. 

 

Agree on trading SNR for EBI  but I would trade SNR for greater PC response than greater gain, all else being equal. A 10% increase in PC response or a 10% increase in gain (already somewhat substantial differences among tubes), I would go with the tube that has that 10% higher PC response. Change up the numbers and it's only a few percent greater PC response while the gain is 10% higher, yeah, stick with the higher gain tube. Tube SNR is measured at much higher light levels than typically encountered in astronomy and while it is a good metric, it's measured in a different operating regime. EBI is the lower threshold, PC response holds across the board, and gain is of value at the lower end of the dynamic range, of course. 

 

EBI indeed sets the threshold but a high gain has no impact whatsoever on how a weak signal can stand out above the EBI. The EBI is thermal electron noise that is getting amplified and if that weak electron signal can't stand out among the electron noise, more gain changes nothing. Now a tube with a higher PC response, under the same conditions, will produce a stronger electron signal while the electron noise is the same. That weaker signal has a better chance of standing out now and greater amplification at this point only makes the image brighter, without improving clarity of the signal. Exception is if the amplified signal is below the visual threshold of the observer but that's a separate matter. 

 

For astronomy in particular, a lot of the magic is in the photocathode itself. Ideally the photocathode introduces no electron noise and produces the strongest electron signal for a given light input. Looking at EBI and PC response allows one to draw a relative figure of merit for the photocathode itself. A tube with a PC that has a higher figure of merit (PC response to EBI) will always produce a cleaner electron signal prior to amplification and will have a lower imaging threshold for really weak optical input signals. Gain just makes it more comfortable for the visual observer. For observers that rely on image stacking with a phone, the optical signal going into the phone is already adequate and a 10% (or greater) decrease in gain will not be perceived as being too detrimental. They should prioritize EBI, PC response, and SNR, in that order. 


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#43 bdg

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Posted 09 June 2019 - 01:53 PM

@ OP please tell me if you feel I am hijacking your thread, I will stop posting.

 

so, I can summarize this by quoting in form of tube specs thread taking  Peter’s tube as the reference. This could be that ideal tube spec and do the trade off on time, color, film, spec parameters accordingly.

*****************************

Type: L3 filmless WP     ——————-> Preferred but thin film tubes can good as film less.
EBI: 0.6                          ——————-> Preferred since it’s  <1 
SNR: 36.9.                     ——————-> Preferred high SNR, but anything at 30 is ok
PR: 2612 uA/lm.            ——————-> Preferred since >2200 Photo Cathode Response 
Gain: 69949 fL/fc.         ——————-> Preferred higher gain for amplifying signal > 62fl/fc. 
Resolution: 72 lp/mm.   ——————-> Preferred since, but 64lp/mm is ok too

****************************

not mentioned in Peter’s spec

Dark Spots: get close to Zero

Bright Spots: get close to Zero

Halo: get <1

****************************

Another question: using NV at prime focus without 1x lens attached, how large does an object look on axis to identify the details. Take for example my TEC 140 with a 0.7x reducer it will be a f 4.9/fl 686mm. This may not be an issue for scanning the sky, but how do you guys get an object of interest on axis to see the details.

 


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#44 Vondragonnoggin

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Posted 09 June 2019 - 03:10 PM

@ OP please tell me if you feel I am hijacking your thread, I will stop posting.

 

so, I can summarize this by quoting in form of tube specs thread taking  Peter’s tube as the reference. This could be that ideal tube spec and do the trade off on time, color, film, spec parameters accordingly.

*****************************

Type: L3 filmless WP     ——————-> Preferred but thin film tubes can good as film less.
EBI: 0.6                          ——————-> Preferred since it’s  <1 
SNR: 36.9.                     ——————-> Preferred high SNR, but anything at 30 is ok
PR: 2612 uA/lm.            ——————-> Preferred since >2200 Photo Cathode Response 
Gain: 69949 fL/fc.         ——————-> Preferred higher gain for amplifying signal > 62fl/fc. 
Resolution: 72 lp/mm.   ——————-> Preferred since, but 64lp/mm is ok too

****************************

not mentioned in Peter’s spec

Dark Spots: get close to Zero

Bright Spots: get close to Zero

Halo: get <1

****************************

Another question: using NV at prime focus without 1x lens attached, how large does an object look on axis to identify the details. Take for example my TEC 140 with a 0.7x reducer it will be a f 4.9/fl 686mm. This may not be an issue for scanning the sky, but how do you guys get an object of interest on axis to see the details.

Yes - that is a smoking good tube. Should give amazing performance for a lifetime of viewing.

 

Mod 3 will have an ocular that is approx 27mm focal length. For prime focus viewing, consider it the same as a 27mm regular eyepiece. Adjust image scale, magnification, and FOV as you introduce reducers or barlows.


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#45 Starman81

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Posted 09 June 2019 - 05:39 PM

 

My advice for most people is that any higher end tube with reasonably good specs will provide for a wonderful viewing experience.

 

 

:waytogo:

 

I second this...  Do your research and prioritize on the most important specs. If you get too overwhelmed, do the best you can price-wise, patience-wise and take the leap. It will revolutionize your observing. 

 

You likely will not be observing with others that have many other NV devices that you can look through and compare views, so it will not be worth agonizing too much over specs. 

 

I bought a 720p 42" plasma TV 12 years ago that is still serving me fine, though I could get a similar size 4K TV for 1/2 the price I paid for the 720p all those years ago. But without a direct side-by-side comparison and not feeling like I'm missing out on anything, stops me from doing so. 


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#46 Eddgie

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Posted 09 June 2019 - 05:41 PM

Yes, that is an outstanding tube.  I know because I have had the chance to view with in many times. 

 

I would not get hung up on the presence of a couple of tiny dark spots in zone 3 or even one in zone 2.   While these can be detected when viewing bright, even surfaces, they will be totally invisible in normal use.  My 10160C/UV has a couple of tiny spots in zone 3, but I have to look hard to see them even on a bright surface.  In all other use, the spots are impossible to see.

 

From my own experience, I would say that the performance difference between most of the tubes I see people buying and the unicorn tubes would be somewhat subtle (as comparing my tubes to Peter's seems to show).  

 

If I could use this comparison:  The typical tube I see most people buying would be like buying a good FPL-53 doublet vs Peters tube, that would be like using an FPL-53 triplet.  For most targets, there is little difference in the view, but with careful comparisons, you can see a difference.  I have had the chance to do sessions with Peter several times, and during colder sessions, I could tell that Peter's tube was slightly better on galaxies, but for most viewing, the difference was very subtle.

 

The real pain of getting a unicorn tube is the acquisition time. One can find a really good L3 tube in stock at multiple vendors, but a Unicorn tube might mean the difference between seeing the summer Milky Way with night vision this year, or with bad luck, having to wait next year to see it.  I can assure you that it will be outrageously good even if you buy an in-stock, high end tube and you will see everything that Peter is able to see (and I speak from experience because I have yet to see something in Peter's tube that could not be seen in mine).

 

 

If you call up today though, and there are some regular high end, in-stock tubes, I can guarantee that the first time you look up and see the incredible detail in the North American Nebula, you will be totally WOWed by any of them. 

 

The view in any of these in-stock tubes will be far more alike than different.  At this level, the difference in the view between this high end. in-stock tube or that high end in-stock tube is likely impossible to see.  A bit of a difference in specs is almost always a zero net sum game.   One might have higher PCR and SN, but higher EBI.  Most of the tubes Richard sells at this grade differ only a little in specs and that is to be expected, because as I understand it, tubes are purchased in set quantities by grade.  Ultimate and TNVC probably buy fixed quantities of high end tubes of a particular grade and when they get low, they order another dozen (or whatever).

 

And these tubes are actually sold to the dealer by model number, which is essentially the tube grade (as is shown in the links I sent above.   The F9800 M22H is the lower grade of F9800 and tubes of this grade will have the minimum spec for the grade). The F9800 M24H is the higher grade of this tube and the minimum specs show where it will excell over the M22H.

 

If you are one of those people that has to own a Takahashi or Astro-Physics though, go for the Unicorn. It never hurts to have the best and some people just don't want to settle for less.  I get that.  


Edited by Eddgie, 09 June 2019 - 06:09 PM.

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#47 bdg

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Posted 10 June 2019 - 04:33 PM

waytogo.gif

 

I second this...  Do your research and prioritize on the most important specs. If you get too overwhelmed, do the best you can price-wise, patience-wise and take the leap. It will revolutionize your observing. 

 

You likely will not be observing with others that have many other NV devices that you can look through and compare views, so it will not be worth agonizing too much over specs. 

 

I bought a 720p 42" plasma TV 12 years ago that is still serving me fine, though I could get a similar size 4K TV for 1/2 the price I paid for the 720p all those years ago. But without a direct side-by-side comparison and not feeling like I'm missing out on anything, stops me from doing so. 

ditto! I ran the panasonic plasma @ 720p as my TV till 2015 and jumped on a Samsung 1080p Plasma and sold the 720p. I wouldn't have changed the Panasonic but Samsung plasma was the last Plasma TV ever made.


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#48 bdg

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Posted 10 June 2019 - 04:50 PM

Yes - that is a smoking good tube. Should give amazing performance for a lifetime of viewing.

 

Mod 3 will have an ocular that is approx 27mm focal length. For prime focus viewing, consider it the same as a 27mm regular eyepiece. Adjust image scale, magnification, and FOV as you introduce reducers or barlows.

thanks 1 Dragon - so pretty much the view will be closer to 36x Mag in a TEC140 @ native FL and 25x with a reducer. Certainly the cropped pictures posted from iPhone makes it look larger :-)


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#49 bdg

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Posted 10 June 2019 - 06:21 PM

How important is gain control? - in theory it may help in light polluted skies and I like having gain control but what about its practical use.



#50 Vondragonnoggin

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Posted 10 June 2019 - 06:33 PM

How important is gain control? - in theory it may help in light polluted skies and I like having gain control but what about its practical use.

If ordering a Mod 3C, get gain control. It’s a nice feature to have.

 

Youll use it frequently to turn gain down to smooth out the view with less scintillation 


Edited by Vondragonnoggin, 10 June 2019 - 06:34 PM.



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